next
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The React Framework
34 lines (33 loc) • 1.15 kB
JavaScript
/**
* FNV-1a Hash implementation
* @author Travis Webb (tjwebb) <me@traviswebb.com>
*
* Ported from https://github.com/tjwebb/fnv-plus/blob/master/index.js
*
* Simplified, optimized and add modified for 52 bit, which provides a larger hash space
* and still making use of Javascript's 53-bit integer space.
*/ export const fnv1a52 = (str)=>{
const len = str.length;
let i = 0, t0 = 0, v0 = 0x2325, t1 = 0, v1 = 0x8422, t2 = 0, v2 = 0x9ce4, t3 = 0, v3 = 0xcbf2;
while(i < len){
v0 ^= str.charCodeAt(i++);
t0 = v0 * 435;
t1 = v1 * 435;
t2 = v2 * 435;
t3 = v3 * 435;
t2 += v0 << 8;
t3 += v1 << 8;
t1 += t0 >>> 16;
v0 = t0 & 65535;
t2 += t1 >>> 16;
v1 = t1 & 65535;
v3 = t3 + (t2 >>> 16) & 65535;
v2 = t2 & 65535;
}
return (v3 & 15) * 281474976710656 + v2 * 4294967296 + v1 * 65536 + (v0 ^ v3 >> 4);
};
export const generateETag = (payload, weak = false)=>{
const prefix = weak ? 'W/"' : '"';
return prefix + fnv1a52(payload).toString(36) + payload.length.toString(36) + '"';
};
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