Dambudziko guru rekutarisa kana tambo ingori nenhamba dzemanhamba nderekuti hapana yakatsanangurwa mwero wekuita izvi. Izvi zvinogona kutungamira kune akasiyana maitirwo anodzosera akasiyana mhedzisiro, izvo zvinogona kunetsa kunzwisisa uye kugadzirisa.
I want to check if a string only contains integer digits numbers. For example: <code>var str = "123"; // return true; var str = "123a"; // return false; </code> A: You can use <code>/^d+$/.test(str)</code>. This will test whether the string consists of one or more digits. If you want to allow for a leading minus sign, then use <code>/^-?d+$/.test(str)</code>. If you want to allow for an optional decimal point and fractional part, then use <code>/^-?d+(.d+)?$/.test(str)</code>. If you want to allow for an optional exponent, then use <code>/^-?(d+(.d*)?|.d+)([eE][-+]?d+)?$/.test(str)</code>. The last two expressions are the ones used by the built-in function <code>isFinite()</code>, which is what you should be using if your goal is to test whether a string can be converted into a number. (If your goal is something else, please edit your question.)
Mamiriro ezvinhu
Conditionals chishandiso chine simba muJavaScript. Vanokutendera kuti udzore kuyerera kwekodhi yako zvichibva pane mamwe mamiriro ari kusangana.
Chimwe chinowanzo shandiswa kune maconditionals kutarisa kana shanduko yakaenzana nehumwe kukosha. Semuenzaniso, ungangoda kuratidza meseji yemhosho kana zvemushandisi zvisiri kushanda.
Unogona kushandisa if statement kuti uone kana mamiriro acho ari echokwadi kana emanyepo. Iyo inotevera kodhi muenzaniso inotarisa kuti uone kana mushandisi wekuisa ari pakati pe1 ne10:
kana (userInput <= 10) {// Ratidza meseji yemhosho } zvimwe {// Ratidza mhinduro yakajairika } Unogonawo kushandisa chirevo chekuchinja kuti uedze mamiriro akawanda panguva imwe chete. Muenzaniso unotevera wekodhi unotarisa kana mushandisi ari pakati pe1 negumi, ane hurefu hwemavara asingasviki matatu, uye anotanga nebhii: chinja (userInput) {cake "10": case "3": case "1": case "a": case "b": case "c": break; default: // Ratidza meseji yekukanganisa }
Kana, Zvimwe
Kana ari ane conditional opareta muJavaScript. Inokubvumira kuti usarudze pakati pezviviri zvinogoneka. Mhedzisiro yekutanga ndiyo mamiriro, uye yechipiri mhedzisiro mhedzisiro yei kana chirevo.
Kana iwe uchida kutarisa kana nhamba iri kunyange kana isingaite, unogona kushandisa inotevera kodhi:
kana (nhamba % 2 == 0) {//even } zvimwe {//odd }
Chimwe chikamu chichaita kana nhamba yacho isiri iyo.
